The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars

TL;DR

This study compares high-resolution spectroscopic measurements of 125 stars with the estimates from the SSPP, revealing the pipeline's typical uncertainties and systematic errors in stellar parameters.

Contribution

It provides an empirical validation of the SSPP's accuracy and uncertainties using high-resolution spectroscopy data for SDSS/SEGUE stars.

Findings

Random uncertainties: 2.4 km/s in radial velocities, 130 K in temperature, 0.21 dex in gravity, 0.11 dex in metallicity.

Systematic uncertainties are comparable to random errors in effective temperature and metallicity.

Validation of SSPP parameters enhances confidence in large-scale stellar surveys.

Abstract

We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R = 2000) spectroscopy. For F- and G-type stars observed with high signal-to-noise ratios (S/N), we empirically determine the typical random uncertainties in the radial velocities, effective temperatures, surface gravities, and metallicities delivered by the SSPP to be 2.4 km/s, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic uncertainties of a similar magnitude in the effective temperatures and metallicities. We estimate random errors for lower S/N spectra based on numerical simulations.